Track-circuit system



March 27, 1928.

A. G. WILLIAMSON v TRACK CIRCUIT SYSTEM Filed April 5, 9 2

2 Sheets-Sheet. 1

IN VEN TOR A TTORNE Y Patented Mar. 27, 1928.

r 1,664,382 PATENT orrrcai'...

ARZBA G; WILLIAMSON, OF CARNEGIE; PENNSYBVHN IA, ASSIGNOR TU PITTSBURGH TRAIN-00111533013 COMPANY, OF- BIT D'SB'URGII, PENNSYIHFANIA, AkGGBfBORETIOIT'OF DELAWARE.

TRACKLeGIiRGUIZE Application-filed Aprilr5, 19.2 2. serialilvo. 5495661..

This invention relates to track. circuit. systems particularly. for. use. in: connection,

. with train control systems of the-type dis? closed. in application Ser. No. 555,304 filed.

April, 18,1922.

In, systems of the character indicatediin. 7 that application the traini is provided? Wltli, twopick-up circuitsone of the indirecttype;

and. the other of the direct type and? the.

10 main. object. of: this. invention. is to provide means whereby a: circuit may beestahlislied. including both rails. of ahlocl'r in. series. andv A turther. object. of the invention is. to

one. form. of the. additional. equipment of the invention appliedthereto;

Rig. 1 is a diagrammatic View. showing the tworailsconnected in parallel; h

Fig. 2. is a diagrammatic view showing a second. form of track circuit with; another form. of the additional" equipment of the invention applied thereto.

Fig. 3 is a diagrammatic view showing; a-

form of theadditional equipment of the invention applied thereto.

Some of the claims in this application are 45. broad enough to cover all three forms ofthe invention shown aswell as other forms' in, which the invention may beclothed, but the particular forms of Figs.- 2 and.3"have been made. the, subject matter offtlwov other 59 applications, Ser. No. 549,662fi1ied-Alpril5',

1922 and; Ser. No. 165,603filed"Fehruary 3;

I 1927; in which these. forms. are. specifically claimed;

. Referring to Fig. 1',,1l andI'Q'represent the Or the second circuit. may. be. lietweenthe tworails in multiple, and ground;

provide means whereby, thev circuit-o between. one rail or the two ralls 1n.mult1p le. and

Other features of'the invention will. ap-

third form of track circuit with. a third rails of. a. traflic. track. divided into blocks; W, andZin-a manner well.understood asby means-of insulation 3:. landhlindi cate. line: wires feda by. the single frequency,- genera'tor G, Associated with; each: block. sia. IIlfllIL transformer indicated. by T, T. 60 and T andlthe. secondary (ioteachot those transformers, is? connected by means of con, ductors. 7, and; 9.. with. primary act a. track:

transformer indicated. variously as. N, N?

and. NP. Secondary. 13: offthe: track trans-v 6 former is. connected by, means of. leads- 16 and; 17 with rail'slv and12itherehy supplying. currents to. both. of. said. rails. of as given! block. These. elements, together. with; a. relay. such as we, rg or re constitutettlie ordinary track. circuit... Connected in parallel with the track. tranformer asuhsidiary transformerindifcatedat M andiM, the pri; mary 11'; of which is; connected by wires. 10. and 12 with conductors. 7. and" and this. 76 subsidiary transformer feeds a. circuit. connected; to oneor bothrails. in. multiple and. ground}, whichscircuit. here. is. as follows: connectedv with. one side. of secondary; 18. is a. conductor. 19 whicl'Lis. grounded; and. con- 80 nect'ed'f with the; other side. of secondary 181- ,is, a conductor indicated'hy. wires 20.523 and. 25;.the; latter. connected: to. lieadlti. 15. and.

24L indicate. impedances, one for. the track circuit. andltlie. other. for the-rail andground" 5 circuit; 21 is a circuit-breaker. interposed in; the. rail and; ground circuit and? this circui'tlbrealier. is actuated". by signal S5, of. the.-pnecedinggblock, by, suitable.- connections asa. 9o Normally. current. will fiowi'n the rails, of. the-tracli circuit. fed by track transformer Nfand-icurrentiwill also low from secondary 185 over wire: 20,. circuit breaker 21, wire 23', impedance} 2'4 wire 25, wire. 1 6, rail 1:, ground5, and; wire 19' hack. to secondary 18. It" Willi he. understood that rail 1 isnot groundedibutlmay. in fact he insulated from I the. ground: Thatisto. say the insulation isof; course not; perfect; and. therev exists a. leakageiofcurnent hutnot. excessive so that voltage: above, ground. potential is maintainedfv on the. rail; Lifithe. railv was. actually grounded; it. wouldlnot' be possible to main- 7 taih this. voltagevandf consequently the direct pickup circuit would not receive an impulse. Wh'en',.therefore-, a= train as K""enters arblocl'i under normal conditions; the indirect and:

direct pick-up circuits carried by the train will both be influenced. The effect of the presence of a train as at K in block Z on the succeeding block Y will be readily under stood. Such train will short circuit-the block Y and a train in block Y would there-' fore not have, its direct pick-up circuit influenc'ed,'- but would nevertheless have its indirect piclcup circuit'influenced because the track circuit of block Y is not affected by the presence of a train inwblock Z: Should a second train advance from block Y into the occupied block 2 it is clear that such second train would not have either its indirect or its direct pick-up circuits influenced. By indirect pick-up circuit is meant a circuit on the trainin inductive relation to the current inthe rails and by direct pickeup circuit? is meant a circuit on the train of an electrostatic character, that is: there is a device on the train in'circuit with one or more rails an d'having a capacity between itself'and ground.

In F ig. 1 is disclosed a modification in, which wire 25 instead of connecting with 1.6'leads to a high resistance 100 bridging the rails so that rails 1 and '2 are connected in parallel with transformer M.

Referring to Fig. 2 the subsidiary transformer is: omittedbut interposed between secondary 6 of the main transformer'and primary 8 of the track transformer is a circuit'breaker in the form of a pole changer P", P and F and connected to Wire 7 between the polechanger and secondary 6 is conductor 101, iinpedance 102, and wire 103 grounded at 104. Also connected between wires 7 and 14 is a shunt 105 around the track transformer. The pole changer may be controlled' either from a signal or a relay.

In" this pa e it isicontr'olled from the signal,

and a relay L If and L which is of the two element type being influenced both by the track circuit and by'currentfrom'transformer T in a manner to be -presently described. Q, indicates a winding affecting. relay- L, this w nding being connected to wires 7 and 9 and therefore fed by transformer T. Accordingly one element of relay L receives current from the track circuit and the other element Q, from the main It is well known that when the instantaneous polarity of bothelements transformer.

is such that the currents in both elements are in phase then armature 100. will swing to right hand position. If the connections of one element should be reversed so that the instantaneous polarity of the currents in the two elements are out of phase then armature 100 will swing to the left hand position.

If current is absent in the track element then controlling armatures 143 and 152.

known that when signal S is at stop or danger position then pole changer P is moved to the left hand position, in which position the instantaneous polarity, of the current in rails of block Y is out of phase with that of element Q and armature 100 of relay L will therefore assume its left hand position and signal S' will therefore assume caution position. Signal S when moving into caution position, will move pole changer l? from left to right hand position, and the polarity of the current in the rails of block X being now such in respect to element Q that armature 100 of relay L will assume its right hand position and'ther'efore signal S will move to clear.

When this occurs signal S will not move pole changer P to any new 13OS1lI1OI1 but said pole changerv will occupy the sameposn tion' as it did under caution conditions.

Assuming now that a train'proceeds in the direction indicated by the arrow, 1t Wlll be understood that so long as current is flowing in the track circuit the indirect piclrup circuit on the train will be influenced and it is only when a trainenters a block such as Z, already occupied by another train, that the indirect pick-up circuit is not influenced by the track circuit.

hen a train K occupies block Z then pole changer P will occupy its right hand position and current from secondary 6 of transformer T will be supplied to the rail and ground circuit as follows: secondary 6, conductor 7, conductor 101, impedance 102, conductor 103, ground 104, rail 1, conductor 14-, shunt 105, conductor 7, pole changer'P conductor 9, and'back to secondary 6. The direct pick-up circuit of a train entering block X will therefore be influenced. In

block Y, however, pole changer P is in the left hand position and therefore that side of secondary 6 of transformer T which is con nected to ground is also connected to rail 1 of block Y and therefore no'current from secondary 6 flows through the rail and ground circuit. Therefore the direct pick up circuit of the train will not be influenced.

Referring now to Fig. 3, here the track circuits are energized by a direct current supplied by battery 150 connected 'to the rails by leads 118 and 117, this current normally energizing relay 151 (marked with'an exponent similar to the block designations) The current supplied for influencing the indirect and direct pick-up circuits of the train is supplied by a battery 110 and an interrupter mary'122 of a transformer-1233, the: second.

ary 124 of Which, is interposed nv ai rail and ground, circuit composed of: said secondary, Wire 125, resistance-126, wire 145.antl groundonone side of said secondary; and wire 141, armature: 143, wire 144, and-wire 11.8, torail 2 on the otherside oi the. secondary. This. current will influence thedirect pick-up circuit carried by. the train. 1.0.9 indicates. a.

relay, controlling armatures 112. andandthis-relay is normally, deenergized; so long. as. relay 151- of the succeeding block is energized. But when a train; enters block X from block W relay 151 will-be deenergized thereby, causing armatures 152 andi143 0t relay 151 todrop. Whenthis occurs a circuit is established. through. back contact 108; as follows: from 108? to. Wire 153, to. relay- 109, wire 155, wire 146.;battery1l0? HIIClEWlIG 156,to, contact 108". Thispicks upiarmatures 112and120 and establishesa circuit through motor 107* as follows: from. battery 1:10 wire 111-, armature112, wire 114', motor. 107?; wire 157', armature 120back tobattery 1110. It also. establishes the previously. described circuit throughinterrupter 106": Thus when no' train is'in block X. no current.- to affect either the indirect or the direct ,pick-up1 circuit is supplied. v

VVhen' a train entersblock Y andsa. train. K is present in block Z'the railv and ground; circuit is ruptured owing tothedeenergiza tion of relay 151 and if; the train. enters blocks .Z with another train already in the block no current will be received; by. saidv secondl train.

Itwill thus be seen that in all=the forms of thisinvention as shown in;Figs. 1, Qaand.

3 two. circuits are present,.one. for the:- in.- direct and the other for the direct; pick-up. circuit; on the train and that; azcircuit breaker is interposedin that circuit offtlie twoiwhich isbetween rail and ground. and: thatrthis circuit breaker iscontrolledi from a preceedingblock.

By the expression pulsating current usedzin the accompanying claims-it isintended to comprehend: both an alternating or, oscillating currentor an interrupted onfluctuating direct: current.

I: claim:

1'. A. track. circuit system; comprising;

traffic rails. divided intoblocks, a: circuit: 111? eluding: both rails in eries, circuits. connectedto: gr und; at ne si -andteat east oneofi the rail a ts others de,v ma n tainingr voltage above ground potential, on. at. least. one. of s i r i s, an a: ci c it. to breaker included in said; second circuit.

controlled by. the first circuit. of a preceding block;

2. A track circuit system comprising;

trafiio rails, divided into. blocks acircuit in- 71s;- cluding both railsin: series; a circuit, QQ Irnected to ground. atone side: and; to at least; one of; the rails atits other: side, for main; tainingvoltage above ground potential on, t least, one of said; rails; a circuit. breake 80. included in said second circuit; and controlled by the first circuit of; a, preceding block, and; a single current sourcesi pplying; current to both of said circuits;

3. A track circuit system comprising z traflic rails; divided intoblocks, a circuit in cluding both rails in. series, acircuihCQn nected togroundat onegside and to. atlfiflzst. oneofg the rails at its other side, for; main.-v taining Voltageabove ground potential 1: m; at least one of said rails a ci it b k r. included in said; second circuitandcontrolled; by the first. circuit of. a; preceding; bloclg, and means tor supplying pulsatingfcurrent; to said circuits.

4.. A track circuit system; comprising: traflic rails divided into.blocks,- a Circuit in cluding both railsin ser es,qa C Ii 1 ',.C0I. nected. to. ground; at one. side, and; ti I at ,1east; one 0i; the rails at; its other side, for main.- taining, voltage above ground potential on: at least: one of said rails,. a; circuit break included in said second" circuit andcontrolled; by the first circuit of Eli preceding blocle. and a. single; current source; supplying p111:- sating current to both of saidicircuits:

5. A track circuit system comprising: trailicrails; divided into, blocks: a circuit, be.- tween; the two railsof; a bloclr andinchl 'ingi two leads-from: a current: source bridging-the rails, a second circuitbetween groundfand; at least one'of said rails, including a cone. ductorconnected; to one ofi said leads and; anothen conductor connected. toa ground for: maintaining" voltage above ground; potential; on at least one Of-saidrailsfand; a circuit; breaker interposedin, said second circuit between the two conductors. V

6.- A. track circuit, system compr sing: trafficrails divided into blocks, a circuit be.- tween thetwo rails of: a bloclnandEincluding; two leads from a currentsource bridging the rails, a second circuit between, ground 1 and; at; least oneof said rails including: a;

conductor connected; to, one: of-said leads; and;

another conductor connected; to. gr,oun,d;,-t'ou maintaining voltage above; ground potent al on at least one of said rails; and; means; forcontr0lling; said secondgcircuit: from the first; circuit ofria:precedingblocki, 1.

7. A track circuit system comprising: traflic rails divided into blocks acircuit including both rails in series, a circuit, connected to ground at one side and to at least one of the rails at its other side, formaintaining voltage above ground potential on at least one of said rails, and means for controlling said second circuit from thefirst circuit of a preceding block.

8. A track circuit system comprising: t-raflic rails divided into blocks, a circuit in cluding both rails in series, a circuit, connected to ground at one side and to at least one of the rails at its other side, for maintaining voltage above ground potential on at least one of said rails, a single current source supplying current to both of said circuits and means for controlling said second circuit from the first circuit of a preceding block.

9. A. track circuit system comprising: traflic rails divided into blocks, a circuit including both rails in series, acircuit, connected to ground atone side and to at least one of the rails at its other side, for maintaining'voltage above ground. potential on at least one of said rails, means for supplying pulsating current to said circuits, and means for controlling said second circuit from the first circuit of a preceding block.

.10; A- track circuit system comprising: traffic rails divided into blocks, a circuit including both rails in series, a circuit, connected to ground at one side and to at least one of the rails at its other side, for maintaining voltage above ground potential on at least-one of said rails, a single current source supplying pulsating current to both of said circuits, and means for controlling -said second circuit from the first circuit of a preceding block.

'11. A track circuit system comprising: traffic rails divided into blocks, a circuit between the two rails of ablock, a circuit be tween ground and at least one of said rails for maintaining voltage above'ground potential on at least one of said rails, a track transformer feeding the first circuit, asubsidiary transformer feeding the second circuit, anda main transformer feeding the track and subsidiary transformers.

12. A track circuit system comprising:-

traffic rails divided into blocks, a circuit between thetwo rails of a block, a circuit between ground and at least-one of said rails for maintaining voltage above-ground'potential on at least one of said rails, two transformers arranged in parallel one feeding the first circuit and the other feeding the second circuit, and a main transformer feeding the first two transformers.

13. A track circuit system comprising: trafiic rails divided into blocks, a circuit between the two railsof a block, a track transformer feeding said circuit, a subsidiary ing the first circuit and the transformer, a conductor between said subsidiary transformer and said circuit, another conductor between said subsidiary transformer and ground vformaintaining voltage above ground potential on at least one of said rails, and a main transformer feeding the track and subsidiary transformers.

lifA track circuit system comprising: traflic rails divided into blocks, a circuit between the two rails of a block, a circuit between ground and at least one of said rails for maintaining voltage above ground potential on at least one of said rails, a track transformer feeding the first circuit, a subsidiary transformer feeding the second circuit, a main transformer feeding the track and subsidiary transformers, and means for controlling the second circuit from the first circuit of a preceding block.

15. A track circuit system comprising: traffic rails divided into blocks, a circuit between the two rails of a block, a circuit between ground and at least one of said rails for maintaining voltage above ground potential on at least one of said rails, two transformers arranged in parallel one feeding thefirst ci'rcuit and the other feeding the second circuit, a main transformer feeding the first two transformers, and means for controlling the second circuit from the first circuit of a preceding block.

16. A track circuit system comprising: trafiic rails divided into blocks, a circuit between the two rails of a block, a track transformer feeding said circuit, a subsidiary transformer, a conductor between said subsidiary transformer and said circuit, another conductor between said subsidiary trans-'- conductors and the subsidiary transformer from the first circuit of a preceding block.

17. A track circuit system comprisingz' traffic rails divided into blocks, a circuit between the two rails of a block, a circuit between ground and at least one of said rails for maintaining voltage above ground potential on at least one of said rails, a track transformer feeding the first circuit, a subsidiary transformer feeding the second circuit, a main transformer feeding the track and'subsidiary transformers, and a circuit breaker in said second circuit.

'18. A track circuit system comprising: traffic rails divided into blocks, a circuit between the two rails of a block, a circuit between ground and at least one of said rails for maintaining voltage'above ground potential on at least one of said rails, two transformers arranged in parallel one feedother feeding the second circuit, a main transformer feeding the first two tranformers, and a circuit breaker in said second circuit.

19. A track circuit system comprising: traflic rails divided into blocks, a circuit between the two rails of a block, a track transformer feeding said circuit, a subsidiary transformer,'a conductor between said subsidiary transformer and said circuit, another conductor between said subsidiary transformer and ground for maintaining voltage above ground potential on at least one of said rails, a main transformer feeding the track and subsidiary transformers, and a circuit breaker in one of the two conductors.

20. A track circuit system comprising: traffic rails divided into blocks, a circuit between the two rails of a block and including two leads from a current'source bridging the rails, a second circuit between ground and at least one of said rails for maintaining voltage above ground potential on at least one of said rails including a conductor connected to one of said leads and another conductor connected togrounthand a circuit breaker interposed in said second circuit between the two'conductors and controlled by traffic conditionsof a preceding block.

21. A track circuit system comprising: traflic'rails divided into blocks, a circuit between the two rails of a block'and including two leads from a current source bridging the rails, a second circuit between ground and at least one of said rails for maintaining voltage above ground potential on at least one of said railsvincluding a conductor connected to one of said leads and another conductor connected to ground, and means v for'controlling said second circuit by traffic conditions of a preceding block.

22. A track circuit system comprising:

traffic rails divided into blocks, a circuit ineluding both rails in series, a-circuit," con-v nected to ground at one side and toat least one of the rails at its other side,. for maintaining voltage above ground potential on at least one of said rails, and means forcontrolling, said second circuit by traffic conditions of a preceding block..

23. A traffic circuit system comprising: tiafiicrails divided into blocks, a circuit between the two rails of a block, a circuit be tween ground and at least one of said ra-ils for maintaining voltage above ground potential on at least one of said ralls, a track transformer feeding the first circuit, a subsidiary transformer feeding the second circuit, a main transformer feeding thetrack and subsidiary transformers, and means for controlling the second circuit by traffic conditions of apreceding block.

24. A track circuit system comprising:

traffic rails divided into blocks, a circuit between the two rails of a block and including two leads from a current source bridging the .rails, and a second circuit between ground and at least one of said rails for. maintaining voltage-above ground potential on at least one of said rails'includinga c'onductor connected to one of said. leads and another conductor connected to ground.

' Signed at Pittsburgh in the county of Allegheny and State of Pennsylvania,'this th day of March, 1922.

' ARBA G. WILLIAMSON. 

